Enjoying and Restoring Our Streams

Children catch stream bugs. Always wash your hands after playing in
the stream.
Credit: Christin of "Wandering thru"

Stream Restoration and Fairfax County Watershed Management Plans

By Adele Kuo

Our neighborhood streams and creeks draw people of all ages,
especially our children, to play at the water’s edge. Exploring a small
stream stimulates all the senses: it provides the delightful burbling
of water trickling over stones, small pools that twinkle with reflected
light, and the melodic chorus of the aquatic life. There are mosaics of
natural outcroppings of stones and plants, fresh air mixed with
wholesome earthiness, and cooler waters that soothe bare feet. Aquatic
vegetation creates hiding places where small critters can be discovered
going about their daily activities. Healthy streams provide the
priceless simple pleasures of exploring nature and deciphering the
surrounding natural environment, even in the midst of our increasingly
built-up world.

What is Stream Restoration?

Stream restoration can take on many forms, and is one of many new
technologies and creative planning tools that can be used to protect
watersheds. Restoration may include practices such as replanting
native vegetation along stream banks, fencing out livestock from the
stream channel, or reshaping the channel to create a stable stream
using natural channel design.

Stream channel evolution in response to increased runoff

Natural channel design seeks to restore the disturbed stream to
emulate the natural stable channel. Stream bank erosion is a natural
process, but can be accelerated by human impacts. When we build
roads, buildings, and parking lots, we increase impervious surfaces,
and more runoff rushes to streams when it rains instead of soaking
into the land. Stream banks are eroded and channels are deepened and
widened. Tree roots are exposed and the incising stream channel
becomes disconnected from its floodplains. Stream buffer zones are
impacted, trees fall and die, and without them soil is left to erode
away. Over time, a new deeper and wider channel will form, and the
stream vegetation will recover, but not before rain carries away huge
amounts of sediment.

A stream restoration that uses natural channel design will imitate
nature while preventing soil erosion. The incised stream channel
cross section is re-graded to a more gentle angle to accommodate
plantings, improve bank stability and reconnect a stream to its
floodplain. Because redesigning streams often removes trees along the
stream edge in order to accommodate the wider channel, stream
restoration can sometimes cause controversy. Unfortunately, if the
stream is left to restabilize on its own in response to increased
runoff flow, the trees will come down regardless, but with much more
soil erosion damage to the watershed. Although natural channel design
projects can be expensive, conventional approaches of armoring banks
with rock rip-rap, berming and concrete channelization can be many
times more expensive and negatively impact aquatic habitat and the
downstream channel.

Across Fairfax County, a pleasant stroll through a typical suburban
community passes sidewalks, streets, homes, and well-kept lawns. Though
it may not seem so, our neighborhoods are directly connected to those
stream ecosystems. The storm drain network, the traditional way of
handling rainfall, sends runoff directly to the streams through
concrete channels and pipes. This prevents street flooding, but has
environmental consequences. In natural systems rain soaks into the
soil, recharging groundwater, but when rain falls on impervious
surfaces like roads, rooftops, and parking lots, it all turns into
runoff.

As a result, when it rains, runoff from the storm drain system
overwhelms our streams. The runoff carries eroded soil particles, yard
debris, trash, oil, and harmful nutrients and chemicals from lawn care.
Water temperature fluctuations impact the ability of fish, amphibians,
and insects to survive or reproduce. The increased quantity of water
flow causes stream bank erosion and other physical changes. Our urban
streams suffer from runoff pollution, erosion, and degradation.

Many residents have witnessed these events occurring in the streams
that pass through their backyards and neighborhoods. Virtually everyone
living in Fairfax County lives within a half-mile of a stream or creek,
and all Fairfax County streams eventually flow into the Potomac River,
Chesapeake Bay, and Atlantic Ocean. What happens in your yard and
neighborhood, or on any parcel of land, affects the water quality
downstream, which in turn affects us all. Habitat is damaged,
recreational and aesthetic value is diminished, and more resources are
needed to treat drinking water.

In 2003, Fairfax County embarked upon a long-term project to develop
comprehensive Watershed Management Plans for each of the county’s
watersheds. Over one million people live in the county’s 400 square
miles. This area is drained by 30 major watersheds – such as Accotink
Creek, Difficult Run and Bull Run, to name just a few. The 30
watersheds contain 980 miles of streams that are as diverse as the
communities that inhabit them, yet they all drain to the Potomac River
and Chesapeake Bay. No matter where you live, work or play, you are
connected to everyone else through your watershed.

The Fairfax County Watershed Management Plans will serve as tools to
identify and address the issues affecting our environment and to manage
the protection, conservation, and restoration of the county’s stream
corridors, wetlands, and other water resources. As of February 2011,
all the Watershed Management Plans have been approved by the Board of
Supervisors. The plans are facilitated by the Stormwater Planning
Division of the Fairfax County Department of Public Works and
Environmental Services (DPWES).

As part of the Watershed Management Plan process, a small tributary of
Big Rocky Run was targeted for stream restoration. A successful stream
restoration attempts to find a stable equilibrium between the stream’s
ecological functions and the urbanized landscape that surrounds it.
(Read more about stream restoration in the box above and follow the
process in photos below.) The primary goals of the project included
stabilizing eroding stream banks and re-establishing a vegetated buffer
to improve the stormwater drainage from a subdivision across a wide,
busy road. To view the Watershed Management Plans that include streams
near you or to learn more about your watershed, visit www.fairfaxcounty.gov/dpwes/watersheds/.

Over the last decades, the way rainwater is handled has changed. As
the Watershed Management Plans emerge and begin to be implemented in
Fairfax County, the health, safety, and function of our watersheds will
continue to play a larger role in the way we plan and manage our
surroundings. We find that stormwater can behave naturally despite
imperviousness and other challenges, and that stream restoration
projects celebrate the rebuilding of a stream to a more stable
condition. Improving the overall health and ecological character of
streams in the midst of suburban Fairfax County invites residents of
all ages to amble down to the water’s edge and enjoy their alluring
qualities.

Before Restoration (View 1)

During Restoration (View 2)

Right After Restoration (View 2)

After Restoration (View 1)

Stream Restoration on a Tributary of Big Rocky Run (in the Cub Run
Watershed)
Stormwater Planning Division, Fairfax County Department of Public
Works and Environmental Services

Adele Kuo is a graduate student at George Washington University
pursuing a degree in Sustainable Landscape Design.